Rewards• One-minute help• Twenty-minutes help• Translation help• List of gold, silver, bronze, iron and colour sponsors


cover Thank you for your help! We will reward it. The reward will increase with your effort and with the effect it has on the quality of the book series.


One-minute help

You can help this project in several ways:

To do more, read on.


Twenty-minutes help – and prizes

The following contributions would be particularly welcome, and we offer prizes for them:

If you can help on any of these topics or you think some issue not included in the text should be added, email me at; I'll consider it for the next edition. All help is welcome.


Translation help

Many readers want translations. If you want to help in translating parts of the text into your language, read about details on how to do it below and then let me know. You will have many readers. Because our non-profit has no funds to pay for translations in advance, we will organize royalties for the translator in each paper book sale.

Translating is fun. A chapter or two are completely sufficient and are very welcome! You do not need to translate a whole volume. And you will learn about physics while doing so. In exchange, I will explain everything that is unclear. But translation is also work - even if Google Translate is used as helping tool. If you have the time for translating, please get in touch. In exchange, I will help you and motivate you wherever I can.

You will get recognition. Your name will be (since 2017) on the external title page (if you translated the whole volume) and on the internal title pages of the text, and of course I will thank you in the text and on the website for your help. And if you have suggestions for improvement, I will do what I can to add them into the text.

Procedure and conditions: To keep the text free for all and of high quality at the same time, a translation requires that you agree to the following conditions and procedure (made simpler in 2019):

If you work with the latex files, here some hints for reading them: